1. Field of the Invention
The present invention relates to a rotation angle detector for detecting a rotational position of a rotor in a dynamoelectric machine such as an alternator, an electric motor, a generator-motor, etc.
2. Description of the Related Art
FIG. 14 is a perspective showing a sensor stator of a conventional rotation angle detector such as described in Japanese Patent Laid-Open No. 2001-136703, for example.
In FIG. 14, a sensor core 2 is prepared by laminating a magnetic steel sheet, for example, projecting portions 2a and slots 2b being alternately formed on an inner circumferential portion of an annular yoke. An insulator 3 is prepared in an annular shape using an electrically-insulating resin, having projecting portions 3a corresponding to each of the protruding portions 2a and slot portions 3b corresponding to each of the slots 2b, being disposed so as to hold the sensor core 2 from opposite sides. Thus, each of the protruding portions 2a and each of the slots 2b are surrounded by the projecting portions 3a and the slot portions 3b so as to be held in an electrically-insulated state. Crossover wire guide portions 3c are disposed so as to stand on the insulator 3 at an outer circumferential end of each of the slots portion 3b. In addition, a connector 4 is formed integrally on an outer circumferential portion of the insulator 3. A plurality of terminal pins 5 are disposed in this connector 4, lead wires 6 being connected to each of the terminal pins 5.
Although not shown, a sensor stator 1 is constructed by winding a winding onto a terminal pin 5 corresponding to a winding start thereof, then winding the winding onto the projecting portions 3a surrounding the protruding portions 2a so as to be guided by the crossover wire guide portions 3c, winding the winding onto a terminal pin 5 corresponding to a winding finish thereof, and then soldering first and second end portions (the winding start and the winding finish) of the winding onto the terminal pins 5.
When a conventional rotation angle detector constructed in this manner is mounted to an actual machine, the temperature in the environment around the rotation angle detector varies. As a result, dimensional changes arise due to expansion and contraction of the insulator 3 and the connector 4, being resin-molded parts. Thus, in this sensor stator 1, because the first and second end portions of the winding are disposed between the crossover wire guide portions 3c and the terminal pins 5 in a state of tension, there has been a risk that tensile stress resulting from the dimensional changes of the insulator 3 and the connector 4 will act on the first and second end portions of the winding and give rise to wire breakages.
Furthermore, in this sensor stator 1, because the connector 4 is disposed on an outer circumferential portion of the insulator 3, the distance between the wound portion of the winding wound onto the projecting portions 3a and the terminal pins 5 is large. Thus, the danger of the first or second end portions of the winding breaking due the tensile stress resulting from the temperature changes described above has been great.
In order to solve problems of this kind, improvements have been proposed which try to suppress the occurrence of wire breakages by shortening the distance between the wound portion of the winding and the terminal pins to reduce the tensile stress resulting from the dimensional changes in the resin-molded parts accompanying temperature changes.
In a sensor stator 1A of a first conventional rotation angle detector proposed as an improvement, an insulator 3A and a connector 4A are prepared separately using an electrically-insulating resin, a plurality of relay terminals 7 are disposed so as to stand in a vicinity of an outer circumference of the projecting portions 3a of the insulator 3A, a plurality of terminal pins 5 are disposed on the connector 4A, and the connector 4A is integrated with the insulator 3A by means of a relay circuit board 8 so as to be positioned on an outer circumferential side of the insulator 3A, as shown in FIG. 15. The corresponding relay terminals 7 and terminal pins 5 are electrically connected by means of a conductor pattern 8a on the relay circuit board 8. Furthermore, a winding 9 is wound onto a relay terminal 7 corresponding to a winding start thereof, then wound onto the projecting portions 3a surrounding the protruding portions 2a, wound onto a relay terminal 7 corresponding to a winding finish thereof, and then the first and second end portions of the winding 9 are soldered onto the respective relay terminals 7.
In a sensor stator 1B of a second conventional rotation angle detector proposed as an improvement, a connector 4B is formed integrally with the insulator 3B using an electrically-insulating resin so as to be positioned on an outer circumferential side of the insulator 3B, and a plurality of terminal pins 5A are insert molded into the insulator 3B and the connector 4B, as shown in FIG. 16. A first end of each of the terminal pins 5A is disposed so as to stand in the vicinity of an outer circumference of the projecting portions 3a, and a second end is formed into a shape projecting inside the connector 4B. Furthermore, a winding 9 is wound onto a terminal pin 5A corresponding to a winding start thereof, then wound onto the projecting portions 3a surrounding the protruding portions 2a, wound onto a terminal pin 5A corresponding to a winding finish thereof, and then the first and second end portions of the winding 9 are soldered onto the respective terminal pins 5A.
In the sensor stators 1A and 1B for a conventional rotation angle detector proposed as improvements constructed in this manner, because the first ends of the relay terminals 7 or the terminal pins 5A are positioned in the vicinity of the outer circumference of the projecting portions 3a, the distance between the wound portion of the winding 9 wound onto the projecting portions 3a and the first ends of the relay terminals 7 or the terminal pins 5 is shortened. Thus, tensile stress resulting from temperature changes acting on the first and second end portions of the winding 9 is reduced, suppressing the occurrence of wire breakages in the first and second end portions of the winding 9.
However, in the first sensor stator 1A, relay terminals 7 and a relay circuit board 8 are required, increasing the number of parts and making the construction of the sensor stator complicated, and one problem has been that the first sensor stator 1A is expensive as far as cost is concerned.
In the second sensor stator 1B, because terminal pins 5A having a complicated shape are insert molding into the insulator 3B (and the connector 4B), one problem has been that the second sensor stator 1B is also expensive as far as cost is concerned.
In addition, in the first and second sensor stators 1A and 1B, the distance between the wound portion of the winding 9 wound into the projecting portions 3a and the first ends of the relay terminals 7 or the terminal pins 5 is shortened, but because the first and second end portions of the winding 9 are disposed in a state of tension between the wound portion of the winding 9 wound onto the projecting portions 3a and the relay terminals 7 or the terminal pins 5, tensile stress resulting from temperature changes acts on the first and second end portions of the winding 9 without being alleviated. Thus, these constructions do not enable the danger of the occurrence of wire breakages to be avoided completely.